Running guides.
Long-form on training, racing, and the math of pace. Written by the PaceCalc editorial team. Free, ad-free, no email gate.
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What Is Zone 2 Running? A Plain-English Guide
Zone 2 running explained: the 60–70 % max HR aerobic-base intensity that builds mitochondrial density, the math behind it, why most runners can't do it without walking, and how to actually find your Zone 2 pace.
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PaceCalc for iPhone is here
PaceCalc is now a native iOS app. Same 20 free running and triathlon calculators, plus race-day share cards. No accounts, no ads, no tracking. Free on the App Store.
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How to Train to Break 4 Hours in the Marathon
A training-focused guide to a sub-4 hour marathon. Mileage targets, a 16-week plan structure, key workouts, fueling, and the common mistakes that cost runners their goal.
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Your First 5K: Complete Beginner's Guide
Everything you need to know to run your first 5K. From walking to the finish line in 8 weeks, with a structured plan, race-day plan, and post-5K next steps.
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Negative Split vs Even Split: Which Race Pacing Strategy Wins?
A practical guide to race pacing. The science of negative, even, and positive splits, when to use each, and how to execute them on flat or hilly courses.
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The Complete Guide to Running Heart Rate Zones
How to find your max HR, calculate accurate training zones using Karvonen, and use zones to balance hard and easy work without overtraining.
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How to Use VDOT to Predict Your Race Times
VDOT is the single best predictor of running performance. Learn what it means, how it relates to VO2max and Riegel, and how to use it for race predictions and training paces.
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Marathon Nutrition: What to Eat Before, During, and After
A practical marathon fueling guide. Carb loading, race-morning meal, gel timing, hydration strategy, sodium, and recovery nutrition — based on current sports science.
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Treadmill vs Outdoor Running: The Science of Why Pace Differs
The mechanism behind why treadmill running feels different from outdoor running. Wind resistance, belt assistance, the 1% incline rule, and what the research actually shows.
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Boston Marathon Qualifying Times: History, Standards, and Cutoffs
A historical and practical guide to qualifying for Boston. How standards have evolved, why the cutoff buffer exists, the current BAA standards, and how to interpret recent cutoffs.